Early degenerative changes of articular cartilage are detected using contrast-enhanced computed tomography (CT) with a cationic contrast agent (CA). However, cationic CA diffusion into degenerated cartilage decreases with proteoglycan depletion and increases with elevated water content, thus hampering tissue evaluation at early diffusion time points. Furthermore, the contrast at synovial fluid-cartilage interface diminishes as a function of diffusion time hindering accurate cartilage segmentation. For the first time, we employ quantitative dual-energy CT (QDECT) imaging utilizing a mixture of three CAs (cationic CA4+ and non-ionic gadoteridol which are sensitive to proteoglycan and water contents, respectively, and bismuth nanoparticles which highlight the cartilage surface) to simultaneously segment the articulating surfaces and determine of the cartilage condition. Intact healthy, proteoglycan-depleted, and mechanically injured bovine cartilage samples (n = 27) were halved and imaged with synchrotron microCT 2-h post immersion in triple CA or in dual CA (CA4+ and gadoteridol). CA4+ and gadoteridol partitions were determined using QDECT, and pairwise evaluation of these partitions was conducted for samples immersed in dual and triple CAs. In conclusion, the triple CA method is sensitive to proteoglycan depletion while maintaining sufficient contrast at the articular surface to enable detection of cartilage lesions caused by mechanical impact.

中文翻译：

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三对比CT方法能够同时评估关节软骨的组成和分割。

使用带有阳离子造影剂（CA）的造影增强计算机断层扫描（CT），可以检测出关节软骨的早期变性。但是，阳离子CA扩散到变性软骨中会随着蛋白聚糖的消耗而减少，而随着含水量的增加而增加，因此妨碍了早期扩散时间点的组织评估。此外，滑液-软骨界面处的对比度随扩散时间而减小，这阻碍了精确的软骨分割。我们首次采用定量双能CT（QDECT）成像技术，该技术利用了三种分别对蛋白聚糖和水含量敏感的CA（阳离子CA4 +和非离子Gadoteridol）的混合物，和铋纳米粒子（突出软骨表面）以同时分割关节表面并确定软骨状况。将完整健康的，蛋白聚糖耗尽的和机械损伤的牛软骨样品（n = 27）减半，并在浸入三重CA或双CA（CA4 +和gadoteridol）中2小时后用同步加速器microCT成像。使用QDECT确定CA4 +和gadoteridol分区，并对浸入双CA和三CA中的样品进行成对评估。总之，三联CA方法对蛋白聚糖的消耗很敏感，同时在关节表面保持足够的对比度，从而能够检测出由机械冲击引起的软骨损伤。和机械损伤的牛软骨样品（n = 27）切成两半，并在三重CA或双重CA（CA4 +和gadoteridol）中浸泡2小时后用同步加速器microCT成像。使用QDECT确定CA4 +和gadoteridol分区，并对浸入双CA和三CA中的样品进行成对评估。总之，三联CA方法对蛋白聚糖的消耗很敏感，同时在关节表面保持足够的对比度，从而能够检测出由机械冲击引起的软骨损伤。和机械损伤的牛软骨样品（n = 27）切成两半，并在三重CA或双重CA（CA4 +和gadoteridol）中浸泡2小时后用同步加速器microCT成像。使用QDECT确定CA4 +和gadoteridol分区，并对浸入双CA和三CA中的样品进行成对评估。总之，三联CA方法对蛋白聚糖的消耗很敏感，同时在关节表面保持足够的对比度，从而能够检测出由机械冲击引起的软骨损伤。